New lubricants and lubricant additives



fluid for the harder metals.

United States Patent 3,199,816 NEW LUBEECANTd AND LUBRICANT ADDKTEVES I-Ming Feng, Waiied Lei-re, Joseph E. Kieninger, Royal Gui-I, and .i'ames B. Hinhamp, Birmingham, Mich, assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Ffied .lan. 27, B60, Ser. No. 4,883 14 Claims. Cl. 252-463) This invention relates to new compositions of matter, particularly to new compositions useful as lubricants and as additives to lubricants, and to processes for manufacturing such compositions.

Numerous compounds and compositions have been proposed as lubricant additives and as lubricants. Hydrocarbon mineral oil in itself does not have all the necessary properties to give completely satisfactory performance in many modern extreme pressure applications such as in gear lubrication and in cutting operations. Through the years the art has proposed many additives designed to make mineral oil more satisfactory in extreme pressure application. These additives do impart some improvement to the lubricity of the oil under extreme pressure conditions but they possess one or more disadvantages which render them markedly less than completely satisfactory. For example, many of them break down in prolonged usage, many are toxic, many are highly colored and opaque so that the operator cannot visually observe the accuracy of his work.

Numerous synthetic lubricants other than hydrocarbon mineral :oil have gone into commercial usage. These synthetic lubricants and additives to improve them in extreme pressure service sufier the same disadvantages as the mineral oil lubricants.

In recent years new types of extreme pressure applications have come to the front. For example, it has long been known that the addition of certain additives-chiefly sulfurized or halogenated materialsto mineral cutting oils improves the cutting operation. By means of such additives it has been possible to conduct a greater number of drills or taps with a given tool before the tool is worn out. But more recently, metals much harder than heretofore have come into commercial being. Prominent among these are titanium and the stainless steels. The cutting oils and additives formerly used on the milder metals have been found unsatisfactory in use in working the harder metals. The drills or taps frequently deteriorate before the first operation is finished. Since the tapping operation is usually the last step in fabrication of a metallic article of manufacture this represents a tremendous economic loss. There is no way to remove a broken tap and salvage the piece of ruined equipment.

Carbon tetrachloride has been proposed as a cutting However, this compound is not effective when used as an additive in mineral cutting oil. It must be used as the sole cutting fluid to be effective. This, of course, introduces serious hazards due to the toxicity of the carbon tetrachloride.

It is an object of this invention to overcome the deficiencies of the prior art relative to extreme pressure lubrication. Another object is to provide new lubricants and lubricant additives. A further object is to provide improvements in extreme pressure lubrication, particularly in the cutting and tapping of metals. An additional object is to provide new compositions of matter and new processes for their manufacture.

According to the present invention, new compositions of matter are provided which consist of the product formed by heating an ester of the formula (XRO) PS,,, wherein X is a halogen of atomic number 17-35, R is a saturated hydrocarbon radical of 3 to 5 carbon atoms 3, i d d l 5 Patented Nov. 5., l 963 "ice and n is an integer from 0 to 1, to a temperature of l30-250 C. for a period of 0.5 to 30 hours, said product being a mixture of volatile compounds and a substantially involatile residue. The substantially involatile residue is characterized by containing phosphorus and halogen, either chlorine or bromine, depending on the halogen in the starting ester. When the starting ester contains sulfur, this element is also found in the involatile fraction. The involatile fraction is more viscous and more involatile than the starting ester. It has a specific gravity greater than unity. it has very high extreme pressure activity.

From the volatile portion of the product we have isolated hydrogen halide, some lower halogenated alkanes, and certain volatile phosphorus compounds including organophosphonates.

Our new compositions of matter have been found to possess unusually good extreme pressure properties. In many instances, particularly in cutting service, they are able to provide satisfactory performance where prior additives have failed completely. The new compositions when used in extreme pressure service are long-lived. They have low toxicity and in many instances, when the starting ester is sulfur-free, are transparent materials which enable the operator to visually follow the course of his work very closely and thereby obtain superior results.

In addition to the new compositions of matter described above, the present invention also includes the process for preparing them which comprises heating an ester of the stated formula to a temperature of -250 C. for a period of 0.5 to 30 hours. This process yields the valuable compositions of this invention.

In carrying out the above process the product formed is a complex mixture whose structure we have been unable to.fu1ly establish. We do know that it consists of a mixture of a volatile and substantially involatile ingredients. For most types of service the mixture so obtained can be used as such as we prefer to so use it either as a primary lubricant or as a lubricant additive. This originally-produced product will be referred to in this specification as the primary produc Under most preparative conditions, this primary product does not constitute the whole reaction product. Unless extreme precautions are taken during manufacture, minor amounts of volatile halogenated non-phosphorus compounds will be removed by vaporization. Prevention of such minor loss is ordinarily neither necessary nor desirable. Our primary product is ordinarily defined as the entire prodnot of the above process less minor amounts of halogenated non-phosphorus compounds. When precautions are taken, however, the primary product can comprise theentire product of the process.

. t is possible to concentrate the substantially involatile portion of the product by relatively mild heating, such as heating to 60-80 C. at a pressure of 5 mm. Such heating completes removal of the highly volatile constituents, which altogether may amount to about 10 percent of the primary product, and which includes a trace of halogen acids, such as hydrogen chloride, and substantial amounts of halogenated alkanes such as 1,2-dichloropropane and 3-chloro-l-propene. In certain types of service wherein a small quantity of volatile material may be objectionable we prefer to carry out such a removal of the more highly volatile materials. This concentrated residual product, which consists of the entire reaction mixture from which has been removed substantially all of the volatile halogenated non-phosphorus components, will be referred to in this specification as the secondary product. This substantially involatile fraction has very high extreme pressure activity.

Another valuable product obtained through practice of this invention is the residual fraction gotten by removing all distillable material from either the primary or secondary product, usually up to a temperature of about 165 C. at 2 mm. pressure. In addition to the highly volatile halogenated non-phosphorus materials mentioned above, this treatment removes substantial amounts of volatile phosphorus compounds, including, when the starting material is tris('2-chloro-isopropyl)phosphite, bis(2-chlorol-methylethyl) (Z-chloro-l-methylethyl)phosphonate and 'b-is(2 chloro 1 methylethyl)isopropenylphosphonate. The total amount of material removed by such distillation may amount to about 55 percent of the primary product. This treatment is useful for applications wherein an absolute of volatile material is essential. The residue from such treatment, which consists of the primary product from which substantially all volatile halogenated and phosphorus-containing product have been removed, will be referred to in this specification as the tertiary produc For most applications, however, no particular advantage is gained by either of the above concentration procedures and since they add to the expense of the process we ordinarily prefer to use the primary product as such.

We have observed that the tertiary product is made up of an acidic portion and a non-acidic portion. A predominant amount of the extreme pressure activity is centered in the former. In certain specialized applications calling for an extremely small amount of active ingredient, we can make still further improvements by performing an acid extraction of the residue from the 165 C. distillation and using the material so extracted (acid fraction) as a lubricant or lubricant additive.

From the above description it is seen that our new compositions embody a range of materials from the complete product of the desired process down through the acid fraction obtained after evaporative and extractive concentration. Certain landmark intermediate concentrates have been referred to above as the secondary and tertiary fractions. It will be understood that these products are mentioned for purposes of illustration only and that valuable products and concentrates are obtained at any stage intermediate between these landmark stages. In other words, it is not necessary to remove all the volatile halogenated non-phosphorus components of the primary product to obtain a valuable concentrate. Moreover, a valuable range of products are obtained by removing only a portion of the volatile phosphorus components of the secondary product. In other words, our invention produces a spectrum of products ranging from the priznary product to the acid fraction, the composition of each product depending upon the degree of concentration and Whether or not an acid extraction is performed.

We have found that our materials give outstanding results both when used as primary lubricants or as lubricant additives. In the latter instance, they are potent materials when added either to a mineral oil base or to a synthetic lubricant base. Such synthetic lubricant bases include silicones, silanes, polyesters, including diesters, polyethers, and the like.

By reference to the above generic formula it is seen that the esters forming our novel compositions are prepared from certain phosphites or thionophosphates. Each esterifying radical of the starting ester always contains 3 to 5 carbon atoms and l halogen atom, either bromine or chlorine. The location of the halogen atom in the molecule is not critical but best results are obtained when it is on the beta carbon atom. Surprisingly, we have found that products formed from esters in which each alkyl group contains only 2 carbon atoms are substantially ineffective, as are phosphate esters which otherwise meet the structural requirements of the starting ester in our process.

All the saturated organic hydrocarbon radicals of 3 to 4 5 carbon atoms are useful in our starting esters. Included are the normal and isopropyl radicals, all the butyl radicals and all the arnyl radicals.

Reference to the above generic formula also shows that our starting esters are always derived theoretically from monohydroxy alcohols as opposed to polyhydroxy alcohols.

Typical starting materials include tris(2-chloropropyl)- phosphite, tris(2-chloro-iso-propyl)phosphite, tris(2-chloro mixed propyl and isopropyDphosphite, tris(3-chloropropyl)phosphite, tris(2. chloropropyl)thionophosphate, tris 3 -chloro-iso-butyl) phosphite, tris (Z-chloro-n-butyl) thionophosphate, and the like. We prefer to use the phosphite esters as starting materials since in general they tend to produce transparent products. Although the products formed from thionophosphates are highly effective in extreme pressure activity they tend to be highly colored and opaque. For this reason, visual observation by the operator is impaired.

Our most preferred starting materials, in terms of effectiveness, color and toxicity, are the tris(2-chloropropyl)- phosphites, in which propyl groups are normal, iso or mixed. w

We have established that the esters which we use as starting materials are in themselves essentially inelfec= tive as extreme pressure lubricants or additives. The heat treatment described above is essential.

In forming our products it is merely necessary to heat the starting ester to a temperature of 250 C. for a period of 05-30 hours. This is preferably done under an inert atmosphere such as nitrogen or rare gas atmosphere but we have found that satisfactory products are obtained when the heating is continued in air. The presence of air in some cases alters the viscosity of the product; sometimes increasing it and sometimes decreasing. it.

When one of our starting materials is heated to temperatures of 130 or sometimes slightly in excess of 130 C. we have observed that an exothermic reaction takes place. Under some conditions the heat generated by this exothermic reaction causes a rather abrupt temperature rise in the reaction mixture. This temperature rise may carry the temperature of the mixture to as high as 250 C. When very good temperature control is maintained the heat from the exothermic reaction can be removed quickly enough so that little or no temperature rise of the reaction mixture is observed. We have found that good products are obtained when the temperature rise is permitted to take place as well as when the process is controlled so as to keep the temperature constant.

Generally speaking, when our starting material is solely one of our starting esters we get best results when the ester is initially heated to a temperature of about C. It is when our starting ester is heated with another starting material of the type described below that very good results are obtained with initial heating up to a temperature of about 130 C.

Our process can be conducted either by heating the starting ester by itself or by heating it with various sulfurcontaining materials, including elemental sulfur itself and various sulfur compounds. The sulfur or sulfur compounds enter into the reaction and the product of the reaction is derived in part from the sulfur-containing starting material. These sulfur materials frequently impart valuable properties to the products although the products formed in such a manner are usually highly colored and opaque.

Our process can also be conducted by heating the starting ester with various chlorinated hydrocarbons among which is carbon tetrachloride. For example, a very outstanding tapping fluid was produced by refluxing tris(2- chloro-l-methylethyl)phosphite with carbon tetrachloride in 1/5 weight ratio under nitrogen for 4 hours followed by vacuum stripping of the excess carbon tetrachloride and hCeating the residue from this stripping for 8 hours at As reaction medium, the starting ester, either by itself or in admixture with an additional starting material of the type described above, can be used. An inert medium, such as relatively high boiling hydrocarbons, can also be used, as can a heat converted phosphorous ester corresponding to a product of this invention. Use of the latter is illustrated in Exmple II.

The following examples describe in detail our new compositions of matter, methods for preparation and compositions containing them.

6 EXAMPLE III Following the procedure of Example 1, trisQfi-chloropropyDthionophosphate is converted to a product which is made up of volatile and substantially involatile fractions and which is a highly eifective extreme pressure agent.

Examples 'IV-XXVI'I, summarized in Table 1, illustrate various reactants and procedures within the scope of this invention and also illustrate formation of primary, secondary and tertiary products as Well as the acid fraction.

Table I.Preparati0n of Products of This Invention Example Starting Ester Other Reactant Tempera- Time, Atm0sture, 0. Hrs. phere IV Tris(Z-chloro-l-methylethyl)phosphite. None 155 8 A r. V dn d 162 0.5 All. VT rln do 162 7.25 Air. V T .do do 160-227 2. 5 Nitrogen VIII Tri%2-chloro1-methyletl1yl)phosphite, Mineral Oil, 95 percent 175-200 16 Do.

5. percent. IX Triiultchloro-iso-propyl)thionophos- None 155 27 Do.

a e 155 0. 5 Do. 155 2. 1 Do. do 155 4.0 Do. iSQB-chloro-iso-propyl)thionophos- Oleie Acid, 1 mole 155 9 Air. XIV Stearie Acid, 1 mole 155 9 Air. XV Ethyl Disulfide, 1 mole.. 155 9 Arr. XV Tert-octyl mercaptan, 1 mole 155 9 Arr. XVII dn Elemental Sulfur, 1 mole 155 9 Arr. XVIII Trish?-chloro-iso-propyl)thioncphos- Suliurized Sperm Oil, 99.5 pereent 155 4 Nitrogen.

phate, 0.5 percent. IX Tris(5-chl0ro-iso-propyl)thionophos- Sulfurrzed Sperm 011, 99.0 percent 155 4 D0.

phate, 1.0 percent. XX Tris(B-chloro-iso-propyl)thionophos- Sulfurized Sperm 011, 90.0 percent.-. 155 4 Do.

phate, 10.0 percent. v XXI Tris(B-chloro-is0-propyl)thionophos- Sulfurrzed Lard 011, 80.0 percent 155 4 Do.

phate, 20.0 percent. XXII Tris(Z-chloro-l-rnethylethyl)phosphite None 162-2 7 5/6 D0. XXIIL do o 130-194 2 5+ Do. XXIV Tris(2-chloro-1-n1ethylethyl)phosphite, Suliurized Sperm Oil, 70 percent 130-195 4 Do.

percent. (ln 185-250 0 5 D0. Tris(2-chloro-butyl)phosphite 160-190 4 0 Do. Tri]s1(2 -bror.no sec -butyl)thionophos- 130-160 30 Do.

p ate. XXVIII Tris(2-chloroan1yl)phosphite 155-165 8 Do.

EXAMPLE I The following three examples illustrate preparation of To a reaction vessel equipped with reflux condenser, liquid addition means and means for measuring gas evolution; was added dropwise 190 parts of tris(2-chlorol-methylethyDphosphite over a period of 2 hours after which the product was allowed to cool to room tempera- :ture. This product, a primary product of this invention, was found to be a highly effective extreme pressure agent either used by itself or as a lubricant additive.

EXAMPLE 11 Two hundred and sixty-eight pounds of tris(2-chloro-1- methylethyDphosphite was added over a period of 6.2 hours to a reactor which contained pounds of tris(2- chloro-l-methylethyDphosphite heated to a temperature of 185-190" C. The entire mixture was maintained under a blanket of nitrogen. The initial feed rate was 5 pounds per hour and this was gradually increased to 25 pounds per hour during the course of the feed. The temperature was maintained at 182190 C. throughout the entire feed period. During the course of reaction a total of 15 pounds of highly volatile material was formed and was removed with the nitrogen gas stream. At the end of the feed period the reaction mixture was heated for an additional hour at the same temperature and then the mixture was distilled at 100 C. and 50 ml. until distillation stopped. A total of 29 pounds and 5 ounces of additional highly volatile material was removed in this fashion. The residual product from this distillation, a secondary produc amounted to 273 pounds (83 percent). Fifty pounds of the total was not formed dining the above processing, but corresponded to the initial 50 pound heel. This can be left in the reactor to serve as reaction medium for a subsequent run.

secondary, tertiary and acid fraction products.

EXAMPLE XX A secondary product of this invention is formed by heating the product of Example I to C. at a pressure of 50 mm. During this heating, distillation occurs whereby volatile halogenated non-phosphorus compounds are removed as overhead. The residue from this distillation, which is a secondary product of this invention is characterized by containing phosphorus and chlorine by being a viscous, clear, water-white liquid and by possessing very good extreme pressure properties. Analysis of a typical secondary product prepared by the general procedure of this example shows 34.5 percent carbon, 5.92 percent hydrogen, 11.0 percent phosphorus and 31.5 percent chlorme.

EXAMPLE )Q(X The secondary product from Example XXH is heated to C. at a pressure of 2 min, thereby removing volatile phosphorus compounds. The residue from this distillation, which is a tertiary product of this invention, has the following characteristics: It is a viscous liquid containing phosphorus and chlorine. The viscosity of a typical tertiary product made by the general procedure of Example XXX is 139.19 centistokes at 20 C. and 50.14 centistokes at 50 C.

Typical analysis of such a product shows 35.0 percent carbon, 6.11 percent hydrogen, 11.6 percent phosphorus and 30.3 percent chlorine.

In general, the compositions of this invention formed from sulfur-free esters range in color from Water-white to pale straw. Compositions prepared from sulfur-containing esters, although possessing very excellent extreme EXAMPLE Q(XI The product from Example XXX is dissolved in petroleum ether and extracted with excess percent aqueous sodium carbonate solution to remove the acidic constituent thereof. The acidic fraction is then liberated by treatment with concentrated hydrochloric acid to a pH esses of the petroleum crude stocks. Such conventional refining processes include distillation, solvent extraction, clay filtration, dewaxing, acid treatment and propane deasphalting. The constituents of mineral oils and greases 5 may be summarized as (1) straight chain paraffins, (2)

branched chain parafiins, (3) naphthenes, (4) aromatics, and (5) mixed aromatic-naphthene-paraflin.

The mineral and synthetic oils to which the present compositions are added may optionally contain additives for a variety of functions. These include viscosity index improvers, detergents, corrosion inhibitors, thickeners, metal deactivators, rust inhibitors, color stabilizers, pour point depressants, emulsifiers, dyes, antioxidants, etc.

The examples in Table II illustrate typical additive compositions of this invention.

Table II.Additive Compositions of This Invention Additive Additive, Concen- Exampie Product of Lubricant tration Remarks Example Weight, percent I Hydrocarbon mineral oil 0. l I do 5.0 III do 10 Z-Ethylhexanoi Solubilizer, 10

weight percent in oil. XXIV do Oleic acid Solubilizer, 20

weight percent. VIII Di-2-ethyl-hexyl sebacate 40 IX Polymethyi siloxane 1. 0 XVII Polyfluorocarbon oil 1. 5 1,1,1-Trichl0roethane solubilizer, 2 weight percent. XXIX Hydrocarbon mineral oil 3. 5 Secondary Product. XXX Tetraalkyl silane 0.3 Tertiary Product. XXXI Hydrocarbon mineral oil 0. 5 Acid Fraction.

VII Polyallrylene glycol of 1.0. The acid fraction is recovered by separating the petroleum ether aqueous phases, drying the petroleum phase over anhydrous calcium sulfate and removal of the petroleum ether by distillation. The acidic fraction, which is recovered as the residue from this distillation, is found to be a highly efifective extreme pressure agent. This liquid material which contains phosphorus and chlorine and which is acidic in nature has extremely good lubricating properties. Analysis of a typical acid fraction shows 14.8 percent phosphorus and 24.0 percent chlorine.

The primary, secondary, tertiary and acid fraction products produced by the above examples are useful as extreme pressure agents when used either alone or as additives to conventional hydrocarbon mineral lubricating oils or to synthetic lubricating oils. When used as additives the amount of compounds of this invention normally ranges between 0.1 and 5 percent.

Much higher concentrations in mineral and synthetic oils can be achieved by use of solubilizing agents. Among the most effective solubilizing agents are alcohols, ketones, saturated and unsaturated carboxylic acids of 8 to 24 carbon atoms, ester and halogenated hydrocarbons. The ratio of solubilizer to active ingredient may range as low as 0.4 to l on a weight basis but best results in terms of solubilizing are obtained when the amount of solubilizer is at least equal to the amount of active ingredient. Throughuse of such solubilizers, concentrations of additives of this invention as high as percent in the oil may be reached.

In general, the compositions of this invention are useful both as primary lubricants and as additives to both natural and synthetic lubricant bases. By way of illustration, typical substrates in which our compositions are used as additives include mineral oils and greases; siliconcontaining oils and greases, including the siloxanes, silanes and sebacate esters; fluoro carbon oils and greases; the diesters such as di-sec-arnyl sebacate and di-2-ethylhexyl azelate; and synthetic oils such as the polybutene oils, other poly olefin oils, poly alkylene glycol oils and tetrahydrofuran polymer oils.

The mineral oils and greases include hydrocarbon oils and greases obtained through conventional refining proc- Other examples of suitable solubilizing agents include 35 poly olefins such as poly isobutylene, poly esters, particularly the arcylates and methacrylates, relatively high boiling hydrocarbon cuts such as kerosene and diesters such as dioctyl sebacate.

A particularly unexpected feature of the present composition is that when they are used as additives to oil bases they actually tend to increase the solubility in the oil of certain other lubricating oil additives. This is true, for example, of lithium, calcium and barium stearates which are used as lubricity and extreme pressure agents.

Numerous tests can be used to demonstrate the re markable extreme pressure effectiveness of the compositions of this invention. One of these is the titanium tapping test. Titanium is a particularly difiicult metal to tap. It is so hard and so destructive of tools that specially adapted taps heretofore have had to be used when working with the metal.

In our tests, standard spiral pointed Mi-20, high speed steel taps were used. No adaption was necessary. The titamum was the alloy designated as 4Al-4Mn, a titaniumalummum-manganese alloy. It has a yield of 140,000 p.s.1., an ultimate strength of 160,000 p.-s.i, an elongation of 15 percent, a reduction in area of 45 percent and a,"

hardness of 36 RC.

The specimens used were thick and were bored vw'th numerous round smooth holes with a diameter of 0.201 inch. The specimen was mounted on a floating table to permit alignment of the center of the hole with the center of the tap. The taps were made in the prebored holes using an automatic tapping machine operated at 267 r.p.m. with a constant force applied in tapping the hole. The tap was preset to penetrate until the first full thread following the chamfered threads at the tip of the tap cleared the bottom of the hole. When the tap reached this pre-determined penetration the spindle reversed its direction of rotation automatically to back the tap out. About 2 ml. of a composition of this invention was used for each tap, one ml. to wet the hole and one ml. to wet the tap. Any amount sufiicient to adequately wet the tap and the hole is adequate.

The effectiveness of a given lubricant was determined by the number of holes a. single tool was able to tap before it broke.

The results of this test, which demonstrate the remarkable superiority of the present compositions, are shown in Table III.

Table III.Tappz'ng Test Results Number of Lubricant Successful Taps Commercially available sulfurized sperm oil Tris (2-ch10r0-l-1nethylethyl) phosphite (untreated) 2 Carbon tetrachloride, 10 percent in sulfurized 5 arm oil- 2 Commercial mixture of sulfurized chlorinated a ditives and lard oil 5 Product of Example XXII, wt. percent in hydrocarbon mineral oil 25 Product of Example I 66 48 Wt. percent treated tris(2-chloro-l methylethyl)phosphite, 2.5 wt. percent lithium stearate, 50 wt. percent 2-ethyl hexanol 45 Product of Example XXIII, 10 wt. percent in hydrocarbon mineral oil 27 Product of Example I, 10 wt. percent in hydrocarbon mineral oil 20 Product of Example XV, 20 wt. percent in hydrocarbon mineral oil 11 Product of Example XVIII 26 Product, of Example XIXM. 25 Product of Example XXII 35 In other tests on MSM-75 grade titanium the material appeared to be superior to any other tapping fluid tried.

In further tests on the cutting of copper a product of this invention made up of 10 percent heat converted tris(Z-chloro-l-methylethyl)phosphite, 10 percent Q-ethylhexanol and 80 percent mineral oil was superior to commercial sulfurized cutting fluids in the following aspects: The test blend gave clean copper chips and work piece which remained stainless in the presence of the test fluid after several days contact with a steel surface. In contrast, conventional cutting oils immediately cause a severe darkening of the surface of the chips and work piece.

Various other tests in which compositions of this invention were used as lubricants or additives in the grinding and cutting of various metals demonstrated a superiority for the present materials as compared to prior art lubricants and additives.

One medium in which extreme pressure activity is useful and in which the compositions of this invention find great utility is in automatic transmission fluids and transaxle fluids, otherwise known as functional fluids. These low-viscosity fluids are ordinarily comprised of a hydrocarbon lubricating mineral oil base containing several additives. Such additives include rust inhibitors such as certain carboxylic acid derivatives and amine derivatives; viscosity index improvers such as polymerized olefins and polymerized acrylate and methacrylate esters, alkyl styrenes, pour point depressants such as olefin-styrene copolymers, antioxidants such as alkylated phenols, aryl amines, etc.; metal deactivators, usually comprising organic nitrogen-sulfur compounds, antifoam agents among which fatty acids and esters are used as well as organic silicone compounds, antisquawk additives, usually sulfurized materials such as sulfurized sperm oil, sulfurized lard and the like. Finally, such functional fluids include extreme pressure agents.

We have found that compositions of this invention are highly effective in such functional fluids both as extreme pressure agents and as antisquawk agents. This effectiveness was demonstrated in actual road testing wherein a function fluid of the type described above was subjected to very severe conditions in diflerential service as follows:

A new differential assembly was installed in an automobile and the assembly was lubricated with a low-viscosity functional fluid containing a composition of this invention. The cm was warmed up by driving for several miles at 40-50 m.p.h. while avoiding fast acceleration or deceleration. The car was then observed for differential noises at speeds up to 75 m.p.h. Then 10-wideopen-throttle accelerations were made from 60 m.p.h. to m.p.h. each followed by a deceleration with closed throttle. Next the car was accelerated from a stop to 50 m.p.h., at this point the transmission was shifted into low range and the car was permitted to coast to a stop with the throttle closed. This acceleration was then repeated to 60 m.p.h. and then to 70 m.p.h. At this point another series of 10-wide-open-throttle accelerations from 60 to 100 m.p.h. were conducted and again the diflerential was checked for noises.

Following the above sequence of 10-wide-0pen-throttle accelerations followed by acceleration from 'a stop to 50, 60 and 70 m.p.h. with accompanying low-range decelerations was repeated four more times. Finally, the car was tested for reverse noise on an 11.6 percent grade. The differential was then disassembled and all parts inspected.

The requirement for this test is absence of noise, wear and gear tooth surface distress.

In such tests a hydrocarbon transaxle fluid containing an additive of this invention at concentrations of 0.25, 0.5 and 1.0 percent gave no noise whereas the noise with other additives ranged from a trace whine to a heavy reverse.

The differential was disassembled and the hypoid pinion and ring gears inspected for tooth condition. The condition is expressed in terms of a numerical scale ranging from 0 (no tooth-surface distress) to 5 (very bad distress). A rating of 3 is borderline. in the tests described above, gears which had been lubricated with functional fluid containing an additive of this invention were rated 0 at additive concentrations of 0.5, 1.0 and 2.0 weight percent in the fluid, both for pinion gear and ring gear deterioration. At an additive concentration of 0.25 weight percent, the rating for the ring gear was 1 and the rating for the pinion gear was 2.

Another test which is widely used to demonstrate the extreme pressure effectiveness of additives and lubricants is the Four-Ball test. The following describes the test and results obtained with compositions of this invention:

Lubricant compositions containing additives of this invention as defined above were tested in a four-ball lubricant test machine to measure their extreme pressure properties. The machine used is known as the Extreme Pressure Lubricant Tester (hereinafter referred to as the El. Tester). The E.P. Tester is described in Engineering, vol. 136, July 14, 1933, pp. 4657. It operates in the range of 10 to 800 kilograms.

The machine utilizes four balls of equal size arranged in a tetrahedral formation. The bottom three balls are held in a non-rotatable fixture which is essentially a universal chuck that holds the balls in abutting relation to each other. Since the bottom three balls are of equal size, their centers form the apices of an equilateral triangle. The top ball is aflixed to a rotatable spindle whose axis is positioned perpendicularly to the plane of the ball holder and in line with the center point of the triangle whose apices are the centers of the three bottom stationary balls.

In operation, the four balls are immersed in the lubricant composition to be tested and the fixture holding the three bottom balls is moved upwardly so as to bring the three fixed lower balls into engagement with the upper rotating ball. As the load is increased, the fixture is moved upwardly and axial of the rotating spindle affixed to the upper ball.

The lubricity of the lubricant under test and therefore the extreme pressure activity of the additive it contains is determined by the amount of wear occurring on the lower balls at the points of contact with the upper rotating ball. If the lubricant is completely effective, the amount of wear will be negligible. On the other hand, if the lubricant is not completely effective under the test conditions, the upper ball may weld or seize to the lower ball due to the heat of friction at the contact points or the wear which occurs will be excessive. If seizure does not 1 1 occur, the average diameter of the circular scar areas of the lower balls is measured so as to give a quantitative basis for comparing the test results with those of other tests. As the severity of the test conditions is increased with a given lubricant composition, the likelihood of excessive wear of the lower balls is increased.

In such tests conventional hydrocarbon lubricating oils were found to cause scar diameters as high as 2 mm. at loads as low as 35 kg. and to seize or weld at loads as low as 90 kg. Even when such oils were fortified with conventional additives to produce a good quality differential hypoid lubricant, seizure took place at 200 kg. However, when a composition (primary product) of this invention was added to the hydrocarbon oil in concentration of only 2.0 weight percent, the scar diameter at loads as high as 210 kg. was only 0.7 mm. and seizure did not occur until loads exceeding 300 kg. were imposed.

In another embodiment of the invention the compositions produced by heat conversion of the starting phosphorus esters may in turn be converted to salts or derivatives which contain certain metals. The metals which are preferred for such conversion are those of groups IIAberyllium, magnesium, calcium, strontium and barium; IIB-zinc, cadmium and mercury; group VIlInotably, nickel and IBcopper, silver and gold. The presence of such metals in lubricating oil has many desirable benefits.

In a typical procedure for preparation of such a salt, the product of heat conversion of tris(2-ch1oro-l-methylethyl)phosphite was heated with A its weight of zinc oxide to produce a zinc-containing mixture which is very viscous. When diluted with its own volume of heat converted tris(2-chloro-1-methylethyl)phosphite this mixture was found to prevent failure in the Four-Ball test at loads higher than 300 kg.

To illustrate the low toxicity of compounds of this invention, a sample of heat converted tris(2-chloro-1- methylethyl)phosphite was found to have an LD in rats of approximately 2.14 mL/kg. and in rabbits of approximately 2.1 ml./kg. Extrapolated to a human of 100 kg'. the LD would be about 210-214 ml.

We claim:

1. The process which comprises heating to a temperature of 155-250 C. for a period of 0.5 to 30 hours an ester of the formula (XRO) PS wherein X is a halogen of atomic number 17-35, R is a saturated hydrocarbon radical of 3 to 5 carbon atoms and n is an integer from 0 to 1 to produce a product containing a mixture of halogen and phosphorus containing compounds volatile at said temperature and a phosphorus-containing residue substantially involatile at said temperature.

2. Process of claim 1 wherein said ester is tris(2-chloro l-methylethyl) phosphite.

3. The product produced by the process of claim 1, said product being a mixture of halogen and phosphoruscontaining compounds volatile at a temperature of 155- 250 C. and a phosphorus-containing residue substantially involatile at a temperature of 155-250 C.

4. As a new composition of matter the product formed by heating tris(2-chloro-1-methylethyl)phosphite to a temperature of -250 C. for a period of 0.5 to 30 hours, said product being a mixture of halogen and phosphorus-containing compounds volatile at a temperature of 155250 C. and a phosphorus-containing residue substantially involatile at a temperature of 155-250 C.

5. As a new composition of matter hydrocarbon mineral oil containing the product of claim 3 at a concentration of 0.1 to 40 weight percent.

6. As a new composition of matter'hydrocarbon mineral oil containing the product of claim 4 at a concentration of 0.1 to 40 weight percent.

7. As a new composition of matter synthetic lubricating oil containing the product of claim 3 at a concentration of 0.1 to 40 weight percent.

8. As a new composition of matter synthetic lubricating oil containing the product of claim 4 at a concentration of 0.1 to 40 weight percent.

9. The process which comprises heating to a temperature of 155250 C. for a period of 0.5 to 30 hours an ester of the formula (XRO) PS wherein X is a halogen of atomic number 17-35, R is a saturated hydrocarbon radical of 3 to 5 carbon atoms and n is an integer from 0 to 1, to form a mixture of halogen and phosphoruscontaining compounds volatile at said temperature and a phosphorus-containing residue substantially involatile at said temperature, and then separating said product by distillation into said volatile and substantially involatile components.

10. The substantially involatile residue produced by the process of claim 9.

11. As a new composition of matter hydrocarbon mineral oil containing the product of claim 10 at a concentration of 0.1 to 40 weight percent.

12. As a new composition of matter synthetic lubricating oil containing the product of claim 10 at a concentration of 0.1 to 40 weight percent.

13. As a new composition of matter, a hydrocarbon mineral oil which contains from 0.1 to 40 weight percent of the product formed by heating tris(2-chloro-1-methylethyl)phosphite to a temperature of 155-250 C. for a period of 0.5 to 30 hours, said product being a mixture of halogen and phosphorus-containing compounds volatile at said temperature and a phosphorus-containing residue substantially involatile at said temperature, said composition being substantially transparent.

14. As a new composition of matter, a synthetic lubricating oil which contains from 0.1 to 40 weight percent of the product formed by heating tn's(2-chloro-l-methylethyl)phosphite to a temperature of 155-250 C. for a period of 0.5 to 30 hours, said product being a mixture of halogen and phosphorus-containing compounds volatile at said temperature and a phosphorus-containing residue substantially involatile at said temperature, said composition being substantially transparent.

References Cited in the file of this patent UNITED STATES PATENTS 2,169,185 Shoemaker et al. Aug. 8, 1939 2,573,568 Harman et al. Oct. 30, 1951 2,722,517 Smith et a1 Nov. 1, 1955 

13. AS A NEW COMPOSITION OF MATTER, A HYDROCARBON MINERAL OIL WHICH CONTAINS FROM 0.1 TO 40 WEIGHT PERCENT OF THE PRODUCT FORMED BY HEATING TRIS(2-CHLORO-1-METHYLETHYL)PHOSPHITE TO A TEMPERATURE OF 155-250*C. FOR A PERIOD OF 0.5 TO 30 HOURS, SAID PRODUCT BEING A MIXTURE OF HALOGEN AND PHOSPHORUS-CONTAINING COMPOUNDS VOLATILE AT SAID TEMPERATURE AND A PHOSPHORUS-CONTAINING RESIDUE SUBSTANTIALLY INVOLATILE AT SAID TEMPERATURE, SAID COMPOSITION BEING SUBSTANTIALLY TRANSPARENT. 